1. Technical Field
The present invention relates generally to heat exchangers and, more particularly, to such heat exchangers having an aluminum extruded header construction and a temperature responsive by-pass assembly.
2. Background
Heat exchangers of the fin and tube type are employed for cooling or otherwise transferring heat between two fluids. Generally, one of the fluids is circulated internally through conduits provided in the heat exchanger core and the other is passed over the exterior of the conduits and associated heat radiating fins. Such heat exchangers are commonly employed in heavy construction machinery as well as other apparatus for use in cooling oil, hydraulic fluid or the like.
In such applications, the fluid may exert a high level of pressure on the heat exchanger and has the potential for subjecting the heat exchanger to even higher pressure spikes. The pressurized fluid may damage the header portion or core portion of the heat exchanger if either portion is not designed properly.
Further, the fluid may have a relatively high viscosity when cool such as at start-up of the equipment and become thinner as it is warmed during use. This high viscosity may cause higher than desired pressure in the inlet header of such heat exchangers due to the viscous resistance of fluid flow through the relatively small passages in the heat exchanger core. Also, the resistance may prevent a sufficient amount of fluid from being circulated through the system which in an extreme case could result in excessive equipment wear.
In view of the foregoing, it would be desirable to provide an extruded header for a heat exchanger for withstanding extreme internal pressure. It would also be desirable to provide a temperature responsive by-pass means to allow the cool high viscosity to by-pass the heat exchanger core. Such a by-pass means may also operate to prevent unnecessary cooling of the fluid thereby assisting the apparatus in reaching a steady state operating temperature more rapidly.